Hi mate,
TBH i started gear far too young many moons ago at 19
I would not advise this as i did not gain to my full potential naturally - this is where alot of us went wrong.
You are only 17 bro and have yrs of natural growth left - only when u have exhausted your natural potential should you make the decision to try anabolics.
There is no special pill that makes you grow into a monster bro - you need to hammer your diet and training and get it spot on and get the rest in - if you continue to do this atm you will continue to gain naturally.
By all means you can read up and research for the knowledge but imho you are far too young even at 18-19 - best left until your 20's at least.